<html>
<body>
   <div tal:define="x string:X;nil string:">
   <p tal:content="x">1</p>
   <p tal:content="x | nil">2</p>
   <p tal:content="python:nil or x">3</p>
   <p tal:content="y/z | x">4</p>
   <p tal:content="y/z | x | nil">5</p>

   <p tal:attributes="name nil">Z</p>
   <p tal:attributes="name y/z | nil">Z</p>
   <p tal:attributes="name y/z | nothing">Z</p>

   <p tal:on-error="python:str(error.value[0])" tal:content="a/b | c/d">Z</p>
   </div>
</body>
</html>
